The invention relates generally to the field of biostimulants, and more particularly to biostimulants composed of humic substances.
Humic substances recovered from fossil materials are widely known to stimulate micro-organisms as well as higher plants and animals. These fossil materials derive originally from peat, which may become carbonized to coal, lignite, leonardite (a naturally oxidized lignite) and similar organic deposits. Humic substances extracted from these fossil materials are much more active as biostimulants than younger soil and aquatic humic substances. However, problems have been encountered in presenting these fossil materials for use as stable solutions and dispersions.
While humic substances can be solubilized at high pH, such solutions are somewhat hazardous to handle, and absorb oxygen, reducing their activity. At intermediate pH, dispersion viscosity increases, causing in some cases the formation of gels which are difficult to handle. Further, mildew problems have been found in this intermediate pH range. At low pH, suspensions are formed which are generally fluid and not very stable. After storage for a short time, sticky bottom sediments are formed which are difficult to re-disperse.
What are needed are methods of providing humic substances in a form which makes them available for use as biostimulants and overcomes the problems associated with physical, chemical and biological container stability problems.
The present invention provides methods of stabilizing humic substances and compositions which are characterized by improved stability on storage, resistance to mildew, and improved bioactivity.
In a first aspect, the present invention provides a stable biostimulant containing acetic acid and a fossil humic substance comprising solid humins and humic acid, wherein the composition contains 5% to about 25%, by weight, organic solids. In one desirable embodiment, the biostimulant composition has a weight ratio of acetic acid to peat humic substance of about 0.08. In another desirable embodiment, the biostimulant composition has a weight ratio of acetic acid to lignite humic substance of about 0.10.
In another aspect, the invention provides a method of stabilizing and increasing the activity of a humic substance. The method involves the steps of mixing fossil humic substances with acetic acid in an amount sufficient that the resulting suspension contains about 5 to about 25% by weight organic solids, wherein the resulting mixture contains about 0.01 to 0.3 parts acetic acid to about 1 part humic substance.
In yet another aspect, the invention provides a method of stimulating plant growth by contacting a plant with a composition comprising a stable biostimulant of the invention.
In still a further aspect, the invention provides a method of stimulating digestion by micro-organisms through addition of a biostimulant of the invention to a substrate to be digested.
These and other advantages of the invention will be readily apparent from the detailed description of the invention.